Method and apparatus for treating fibrous material



Jan. 4, 1944. s, BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4Sheets-Sheet 1 Jan. 4, 1944.

s. BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4Sheets-Sheet 2 uawaxwagxmx Jan. 4, 1944. s. BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4Sheets-Sheet 3 fiy Z I 1 FT s. BOGATY Jan. 4, 1944.

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4Sheets-Sheet 4 Patented Jan. 4, 1944 METHOD AND APPARATUS FOR TREATINGFIBROUS MATERIAL Stanislaus Bogaty; Philadelphia, Pa., asslgnor toProctor & Schwartz, Incorporated, Philadelphia, Pa., a corporation ofPennsylvania Application July 5, 1940, Serial No. 344,181

Claims.

This invention relates to treating, and particularly drying, animal,vegetable, mineral or synthetic fibrous stock spread in a layer ofsubstantially uniform thickness on a foraminous support adapted totravel in a horizontal plane longitudinally through a suitable enclosurewherein the stock is contactedby moving currents of a gaseous treatingmedium enroute.

Prior to the present invention the drying medium has been directeddownwardly against the entire area of the layer of stock simultaneously,in order to maintain the stock in position on the foraminous supportconstituting the upper run of an endless belt conveyer.

In order to avoid packing of the stock on the conveyer, in someinstances, the circulation of the air in successive sections throughoutthe length of the drying chamber, has been alternately reversed.However, with this method, it has been necessary to provide a second orholddown conveyer of a foraminous character, in superposed relation toand traveling concurrently with the conveyer on which the layer of stockis placed, in order to prevent the stock from being blown oil thecarrying conveyer. This arrangement entails additional expense, both inthe initial installation and subsequent maintenance of the apparatus. (w

Another disadvantage of the hold-down system is, that, in order toobtain reversals of the air, it is necessary to provide partitions orother means at spaced intervals throughout the length of the dryingchamber to control the paths of movement of the reverse air currents,and to provide means for producing the circulation in each of thepartitioned sections. Such arrangements place a definite restriction onthe number of times the passage of the air through the stock can bereversed within the length of the drying. I chamber.

The object of the present invention is to create a wave-like alternatingcompressive and expansive action in the stock, perpendicular to theplane of the foraminous support, in successive localized transverseareas of the layer, progressively, as the foraminous support transportsthe layer of stock longitudinally through the enclosure.

Another object of the invention is to confine the layer of stock on thesupport against shifting of any substantial portions thereof parallel tothe support, to prevent development of holes through the layer and aconsequent rushing of the drying medium therethrough which would disruptthe aforesaid wave-like compressive and expansive action in the stock.

The construction and operation of a drier made and operated inaccordance with the principles of the present invention will be fullydescribed hereinafter, reference being had to the accompanying drawings,of which:

Fig. 1 is a longitudinal section elevation of one end of the drier;

Fig. 2 is a transverse sectional elevation taken on the line 2-2 of Fig.1;

Fig. 3 is an enlarged detail of the invention;

Fig. 4 is a view similar to Fig. 1, showing the preferred form of nozzleand conveyer construction; and

Fig. 5 is' an enlarged view of a portion of the structure of Fig. 4,illustrating the Wave-like compressive and expansive action morethoroughly.

As shown in Figs. 1, 2 and 4, the drier comprises a suitable casing l ofany desired construction and dimensions and comprising suitablyinsulated enclosure walls 2, 2. Extending horizontally throughout thelength of the casing I, in vertically spaced relation to the base orfloor line 3, is an imperforate false bottom 4.

Spaced above the horizontal false bottom 4 is a carrying run 50. of anendless belt conveyer 5, the return run 517 of which is disposed in achamber 6 formed below the false bottom 4.

The conveyer 5 may be composed of wire mesh screen, as shown at l inFigs. 1 and 2, but preferably the foraminous support is composed ofperforated sheet metal, as shown at H in Figs. 4 and 5.

The foraminous body i' or 11, as the case may be, is supported atintervals throughout its length by transversely extending girts 8, 8.The girts, as usual, are secured at their opposite ends to side chains9, 9 forming part of the conveyer,

and the side chains 9, 9 travel, as usual, on'

suitable supporting rails l0, III, which in turn are supported in anysuitable manner by the framework of the drier. If desired, the belt 5may be made in sections pivotally connected at and to the cross girts 8,8, this being a well known conveyer construction.

At each side of the foraminous body I, or 11, of the conveyer, the sidechains 9, 9 are provided with vertically extending side flanges II, II,to prevent escape of air and material laterally over the side edges ofthe carrying run of the conveyer.

Arranged above the carrying run 5a of the conveyer 5 is a series of airmanifolds I2, i2. Each manifold l2 comprises a hood l3 of a generalpyramidal form, to the apex of which is connected an air conduit M.Connected with the conduit I4 is the discharge side of a fan or blowercasing l5. A suitable fan or blower I6 is rotatably mounted in thecasing 15 on one end of an armature shaft ll projecting downwardly froman electric or other suitable motor mounted outside the casing I.

Air is driven under pressure by the fan or blower l6 into the conduitl4, and flows downwardly through the hood l3 of the manifold l2 onto thelayer X of the fibrous stock undergoing treatment in the drier. Asubstantial portion of the air passes through the stock and theforaminous support I, or 11, to the space below the carrying run 5a ofthe conveyer, from which the air moves laterally across the false bottom4 to and upwardly through a suitable passage at one side of the driercasing I, around the supporting rail ID at said side of the conveyer 5,from which the air is drawn by the fan or blower I6 into the blowercasing I5 for movement into the conduit I4 and a repeat of thecirculating cycle.

Between the conveyer rail I0 and one of the side walls 2 of the driercasing I, the air in circulation passes through a suitable heater orconditioning unit I9 of any well known type, whereby the air is heatedor otherwise conditioned in circulation.

To prevent free particles of the fibrous material which are entrained inthe circulating air from entering or passing through the unit I9, adouble filter screen 20 is provided. The filter 20 consists of an upperrun 20a and a lower run 20b of an endless belt composed of fine meshscreen, the side chains of said belt being supported by suitable rails2|, 2|. The material retrieved by the filter conveyer 20 is carriedthereby outside the drier casing I, and removed from the conveyer in anysuitable manner, whereby the filter screen is retained in a cleancondition and presents substantially no retarding effect on thecirculation of the air therethrough.

In Figs. 1 and 2, the bottom of each of the manifolds I2 or the hoods I3thereof is composed of a plurality of transversely extending slats 26,26 which are spaced apart laterally to form air slots 21 21therebetweeh, through which the air driven into the hood I3 by the fanor blower I6 is directed downwardly into contact with the layer X ofstock supported by the carrying run 5a of the conveyer 5.

The blower I6 is operated to build up an air pressure within the hoodI3, and the slots 21 are adapted to increase the velocity of the air asit escapes from the hood. The slots 21, 21

direct the air downwardly, in perpendicular relation to the layer ofmaterial X, in sheet-like streams having their lengthwise dimensionsarranged transversely to the conveyer surface 5a, with the plurality ofstreams disposed in laterally spaced parallel relationship to eachother, throughout the length of the drying chamber.

The air driven through the slots 21, under pressure, and moving atrelatively high velocity causes the central planar portion of eachsheetlike stream of air to contact with and pass through the layer ofmaterial X directly below and in alignment with the slot, as indicatedby the arrows a. This causes the stock to be compressed as it passesunder each slot 21, an indicated at b in Fig. 1.

According to the principles of the present invention, the material lyingintermediate the parallel compressed areas I), b, as indicated at c, c,is caused to be raised upwardly with respect to the conveyer surface 5a,and to be fiufied by eddy currents of air, indicated by the arrows d,which are created as 'a side-wash to the central planar portion a ofeach stream.

To effect the formation of the above-noted eddy currents, the lowerportions of the air slots 21, along the side edges of each slat 26, areflared outwardly and downwardly at and with respect to the centralvertical plane of each slot 21. The air under pressure, and traveling atrelatively high velocity through the slots 21, passes downwardly andexpands laterally as it leaves said slots. edges of the adjacent slats26, 26 govern the state of divergence of the side-wash currents d toproduce the eddy currents. The rising and flufiing of the stock iscaused by the eddy currents swirling above and penetrating the stock "inthe areas c-c intermediate the compressed extending spikes or pins 30,distributed uniformly over its entire surface, at relatively-spacedpoints laterally and longitudinally thereof. The pins 30 are adapted toproject into the layer of material X and prevent any lateral shiftingthereof with respect to the carrying surface 50. of the conveyer.

The slatted bottoms 25, 25 of the several manifolds I2, I2 located sideby side throughout the length of the drying chamber form a roof over thecarrying run 5a, and the sheet-like streams of air passing downwardlyagainst and perpendicular to the layer of material X on the carrying run511. of the conveyer 5 return any loose fibre that may be freed from thelayer X'by the raising and ilufling resulting from the penetration ofthe layer by the eddy currents. The eddy currents, by striking the undersurface of the slatted wall 25, are turned toward the downwardly drivingstreams of air flowing through the slots 21, and carry loosenedfibres'back into the streams, to be returned thereby to the layer X onthe conveyer surface 511.

As shown in Figs. 4 and 5, the bottom I25 of each of the air manifoldsis formed with a series of slots I21 extending transversely to the pathof movement of the foraminous support 11 for the layer X, at spacedintervals along said path of movement.

The slots I21, I21 are disposed in a horizontal plane intermediate thebottom I25 of the manifold and thetop of the layer X of fibrous stock,and are formed by the laterally spaced lower terminal edges I28, I28 ofupwardly divergent walls I29, I29 of each nozzle I30, the angle ofdivergency e--e of the side walls I29, I29 being equal at the oppositesides respectively of the central vertical plane j of the nozzle, whichis perpendicular to the plane 9-9 of a foraminous stock supportingsurface 11, whereby the v air is delivered downwardly against the uppersurface of the layer of stock X in sheet-like streams y y perpendicularto the surface 11, and effects compression of the stock in relativelynarrow localized transverse areas :r-r, spaced apart along the length oftravel of the foraminous supporting surface 11 for the layer X.

While a substantial portion of the air of each stream 11 passes throughthe perforations 18 of the surface 11 a goodly portion of the airimpinges against the solid portions 19 of the surface 11 and isdeflected upwardly and laterally with respect to said surface and thegeneral The divergent portions 28, 28 of the vertical plane of thestreams y, as indicated by the arrows yl, Fig. 5. These deflectedupwardly traveling portions yI, yI of the air streams raises and fiuifsthe stock in the areas :cI, ml which lie intermediate the compressionareas :0, :r, the raising and fluifing areas :nI, :rI being relativelywider than the narrow, compression areas it, 2:, between which the widerfiufllng areas extend from side to side of the longitudinally movingforaminous surface 11 by which the layer X is transported through theenclosure].

As the surface 11 transports the layer of stock X through the enclosureI, it serially ing tercepts the vertically moving streams of air 1 y andthe alternating compressions and raisings in the areas a: and mlrespectively progress along the advancing layer of stock. This causesagitation of the stock in the layer which disintegrates lumps in thestock which cannot be mechanically broken up without breaking the fibresof which the matts or lumps are composed.

In order to obtain a satisfactory compressive and expansive action thewidth w of the slots I21, I21 should bear a definite relationship to thespacing s of the slot centers. that the ratio of not less than 6 to 1between the spacing s of the centers f, j of the nozzles I30, I30 andthe widths w of the respective slots I21 will give satisfactory results,with the best results obtained, for example, under an approximate 24 to1 ratio, as shown in Fig. '5. While even higher ratios may be employedit has been found that the stock, under such circumstances, has atendency to lie dormant during a portion of its travel betweensuccessive nozzles. The best results are obtained by keeping the stockin motion, perpendicular 'to the support as it is conveyed horizontallyby the support. Consequently, when using a ratio between a minimum of 6to 1 and a maximum of 30 to 1, a constant agitation is effected. With aratio below the minimum noted above, the downward pressure becomes moreor less universal over the entire area of the layer X.

In some instances it may be advisable to provide a differential action,as the layer X is transported through the dryer. For example, a quickaction may be desirable at and adjacent the entrance to the dryingchamber with the cycle periods increasing in length as the stockadvances toward the exit from the drying chamber, or the reverse may beresorted to under different circumstances with different materials, i.e. the cycles may be longer in the portion of the chamber adjacent theentrance and shorter in the portion near the exit.

Such differential action may readily be accomplished by spacing thenozzles I21 differently or in increasing or decreasing progression withthe maximum and minimum ratios noted above.

During the compression and expansion of the stock, as the stock travelshorizontally, the stock slides up and down along the vertical pins 30,3|] which function as guides for the stock and keeps it from shiftinghorizontally on and relative to the foraminous supporting surface 11.

As shown in Fig. 5, the common plane of the lower terminal edges I28,I28 of the nozzle slots I21, I 21 is spaced below the plane of thebottom wall I25 of the manifold I2, and the divergency of the side wallsof one nozzle I30 with respect I to the side walls of the adjacentnozzles I30 produces ,air spaces a, z with angular deflecting surfaceszI, a2, 22 by which the air is turned and It has been found v 3 directeddownwardly and into the paths of discharge from the nozzle slots I21,I21 by which more or less swirling eddy currents corresponding to thosepreviously described are produced.

It will be understood that the endless belt 5 in each of the structuresof Figs. 1 and 2, and

Figs. 4 and 5 preferably extend beyond the opposite ends of the drier Iand around suitable supporting drums or wheels; and that the belt as awhole may be driven from any suitable source of power through anysuitable form of transmission without departing from the present Ipenetration of the layer of stock beneath said face within each of saidnarrow areas by said impinging streams of air, and expanding relativelywider intermediate areas of said layer by deflecting portions of saidair streams laterally therefrom into said intermediate areas of thestock.

2. The method which consists in pneumatically compressing relativelyspaced narrow areas of a layer of fibrous stock simultaneously at fixedpoints respectively along a, path of intended travel of said layer byimpinging streams of air against one face of the layer within saidnarrow areas respectively, effecting penetration of the layer of stockbeneath said face within each'of said narrow area by said impingingstreams of air, expanding relatively wider intermediate areas of saidlayer by deflecting portions of said air streams laterally therefrominto said intermediate areas of the stock, and advancing said layeralong said path relative to said fixed points to effect saidcompressings and expandings alteriiately throughout the length of saidtraveling ayer.

3. The method which consists in advancing a continuous layer of fibrousstock horizontally, pneumatically compressing narrow transverse areas ofsaid layer simultaneously in transverse planes perpendicular to saidlayer and spaced apart longitudinally of the path of travel of saidlayer by impinging streams of air against one face of the layer withinsaid narrow areas respectively, effecting penetration of the layer ofstock beneath said face within each of said narrow areas by saidimpinging streams of air, and expanding said stock in relatively widertransverse areas intermediat said narrow compression areas as said layeradvances through said perpendicular planes successively bydefiecting'portions of said air streams laterally therefrom into saidintermediate areas of the stock.

4. The method which consists in supporting a continuous layer of fibrousstock on a foraminous surface in a horizontal plane, directingsheet-likestreams of air downwardly against said layer simultaneously intransverse planes perpendicular to said layer and said surface at spacedintervals longitudinally thereof, and advancing said surface and saidlayer concurrently in said horizontal plane through said perpendicularstreams of air, compressing the stock in relatively narrowareasrespectively at said perpendicular planes by said sheet-like streams ofair respectively, and expanding said stock intermediate said compressionareas progressively along said layer as said layer passes through saidair streams by deflecting portions of said sheet-like streams laterallytherefrom into the stock disposed intermediate said compression areas.

5. The method which consists in supporting a continuous layer of fibrousstock on a foraminous surface in a horizontal plane, directing sheetlikestreams of air downwardly against said layer simultaneously intransverse planes perpendicular to said layer and said surface at spacedintervals longitudinally thereof of at least six times the thickness ofeach of said air streams, advancing said surface and said layerconcurrently in said horizontal plane through said perpendicular streamsof air, compressing the stock in relatively narrow areas respectively atsaid perpendicular planes by said sheet-like'streams of-airrespectively, and expanding said stock intermediate said compressionareas progressively along said layer as said layer passes through saidair streams, by deflecting portions of said sheet-like stream passingdownwardly and completely through said layer of stock and perforationsin the underlying foraminous surface and compressing the stock inrelatively narrow areas at said planes respectively with other portionsof the air of each stream impinging againstimperforate portions of saidforaminous surface and rebounding upwardly and thereby expanding saidstock in areas intermediate said compressed areas, and advancing saidsurface and said layer concurrently in said horizontal plane throughsaid perpendicular streams of air.

7. The method which consists in supporting a continuous layer of fibrousstock on a foraminous surface in a horizontal plane, directingsheet-like streams of air downwardly against said layer simultaneouslyin transverse planes perpendicular to said layer and said surface atspaced intervals longitudinally thereof, advancing said surface and saidlayer concurrently in said horizontal plane through said perpendicularstreams of air, compressing the stock in relatively narrow areasrespectively at said perpendicular planes by said sheet-like streams ofair respectively, and expanding said stock intermediate said compressionareas progressively along said layer as said layer passes through saidair streams, by deflecting portions of said sheet-like streams laterallytherefrom into the stock disposed intermediate said compression areas,and confining the layer of stock against substantial movement parallelto said surface during movement of said stock perpendicular to saidsurface.

8. A drier for fibrous stock, comprising a continuous flat foraminousconveyer surface operable in a horizontal plane for supporting andtransporting said stock in a continuous layer longitudinally through thedrier, a plurality of air nozzles disposed above said surface and eachincluding a pair of opposite symmetrically shaped side walls forming along narrow air discharging slot extending transversely of said surfacewith said slots spaced apart along the path of movement of said surfaceand the layer of stock thereon and arranged to direct air downwardlyagainst said layer in sheet-like streams in planes perpendicular to saidsurface and said layer of stock to compress said stock in narrowtransverse longitudinally spaced areas thereof simultaneously as saidlayer of stock is advanced through the drier 0n and by said surface,means for forcing air under pressure from said discharge slots to effectsaid compressions and penetration of the stock by the air of saidstreams, and imperforate areas in said foraminous surface to deflectportions of the penetrating air,laterall through the stock therebyexpanding the stock intermediate said compression areas.

9. A drier for fibrous stock, comprising a continuous flat foraminousconveyer surface operable in a horizontal plane for supporting andtransporting said stock in a continuous layer longitudinally through thedrier, a plurality of air nozzles disposed above said surface and eachincluding a long narrow air discharging slot extending transversely ofsaid surface with said slots spaced apart along the path of movement ofsaid surface and the layer of stock thereon and arranged to direct airdownwardly against said layer in sheet-like streams in planesperpendicular to said surface and said layer of stock to compresssaid-stock in narrow transverse longitudinally spaced areas thereofsimultaneously as said layer of stock is advanced through the drier onand by said surface, means for forcing air under pressure from saiddischarge slots to effect said compressions and penetration of the stockby the air of said streams, and imperforate areas in said foraminoussurface to deflect portions of the penetrating air laterally through thestock thereby expanding the stock intermediate said narrow transverseareas, said slots being spaced apart a distance at least as great as sixtimes the width of each slot in order to allow for said expansions ofthe stock intermediate said compressions thereof.

10. A drier for fibrous stock, comprising a continuous flat foraminousconveyer surface operable in a horizontal plane and composed ofperforated sheet material for supporting and transporting said stock ina continuous layer longitudinally through the drier, a plurality of airnozzles disposed above said surface, means for forcing air underpressure through said nozzles, each nozzle comprising oppositelydisposed symmetrical walls forming a long narrow air discharging slotextending transversely of said surface with said slots spaced apartalong the path of movement of said surface andthe layer of stock thereonand arranged to direct air downwardly against said layer in sheet-likestreams in relatively spaced planes perpendicular to said surface, witha portion of the air of each stream passing through said layer of stockand the perforations of said sheet to compress the stock in narrowtransverse areas below said slots, and with other portions of the air ofeach stream impinging against solid portions of said sheet surroundingsaid perforations and being thereby deflected upwardly into said layerof stock to expand said stock in areas intermediate said compressedareas, to effect drying action in said layer of stock progressivelyalong the length thereof.

STANISLAUS BOGATY.

